The goal is to study the abnormal differentiation of leukocytes and to establish better methods for the diagnosis and classification of leukemias and lymphomas. The techniques consist of light and electron microscopy, and immunocytochemistry, scanning electron microscopy and tissue culture. A firm theoretical and technical basis for this investigation has been established in previous studies on the differentiation and function of normal leukocytes from humans and experimental animals. This work will: (1)\establish better techniques for applying histochemical and immunochemical stains to the diagnosis of leukemias and lymphomas by light microscopy; (2)\more accurately define the specific cell types involved in leukemia and lymphoma thereby providing new markers for cell lineage, which should eventually permit a more precise correlation with protocols of therapy; (3)\clarify certain aberrations in the step-wise assembly of cellular organelles such as granules during leukemic differentiation, particularly "undifferentiated" leukemias and perhaps preleukemias; and (4)\further characterize the stromal cells (alkaline-phosphatase positive reticulum cells) of normal and myeloproliferative disorders in vivo (biopsy) and in vitro (Dexter culture) by assaying their procollagen products by DEAE-cellulose chromatography.